sleepless

[H@nk]

On a sleepless night, a few nights ago, I had to think about this one. I saw the other day a little movie on you tube about building a surfboard. Made from polystyrene. Should it be possible to make the side-walls out of this material? When you use polystyrene thikness 2", working next with the molding paste, and after all doing it with epoxy and glassfiber?
Just wondering

[Geron]

This will be an interesting one. Let's here from the experienced.

What about punctures -- but they would be very easily fixed.
Would it have to be glassed inside and out???

Layers of thin polystyrene for the curves???

Bulkhead polystyrene also -- I'm thinking light really light.
Hatch -- built from a form or glued together?

Has anything like this been done before?
Does it emit harmful gases??
So many questions.

Good Post H@nk Got me thinking.

Geron

[Dee Bee]

There was a post on this before somewhere....

What I remember is that the stresses on a TD are different than on a surf board.

One of the challenges would be holding the TD together where the corners meet and also the load bearing of the hatch

Additonaly it is an expensive process to do an the scale of a TD.

Just what I remember...

Dee Bee

[alloffroad]

Howabout doing just parts of it. Like the gally hatch it self, the entry door(s).

[H@nk]

Maybe the inside made of 3 mm birch, glue the polystyrene on it, make curves and wholes for windows and door(s) and the shape you like. And after all the epoxy with 1 layer of fiberglass.

[QuietOutdoorsman]

Just offering an opinion here. I don't have any experience with polystyrene, but in the past few years I have gotten a lot of carbon fiber laminate part design and stress analysis. Carbon fiber is great if you can mold the structure as a single part and not put a single hole anywhere. The weakest part of the design with multiple parts is the bolted joints. You CAN NOT drive a screw into this material and expect it to hold very well.

From what little I know of surfboards, they have a foam core with polystyrene laminate over that core. This is very similar to honeycomb core parts I've dealt with. Very strong in bending, terrible in shear. With the torque box design most are utilizing, the walls, roof, and bulhead wall take considerable shear loads.

Now, all that being said....you could make this work. You have to design the outer shell (walls & roof) as one part. The bulkhead wall would have to be bolted in. Bolts....not screws. This is possible, but I wouldn't think it worthwhile. Of course this is the conservative engineer in me!

[Miriam C.]

If you get it too light it will surly blow away.

[starleen2]

I think Dave (bluebonnet tear) is doing a similar fiberglass build??

[zukamini]

I played with this concept a few years back for a light weight dingy, as Outdoorsman stated , the shear strength is not that good. however , by using 1/8" poplar ply sandwiching the polystyrene in a composite form you will have a very light and strong construction. I would stay away from polyester resin used in fiberglass, as it will dissolve the polystyrene foam very quickly. epoxy is the way to go, and if your familiar with stitch and tape construction used in fast boat building. the dingy turned out good and only weighed 30lbs. for a 8ft. x 5ft. dingy. as for the bends ,such as the curvature in the roof line, 1" foam with relief cuts every 6" or so will work, sand and stager second 1" foam over relief cuts. keep the gaps as tight as possible as extra epoxy will be required to fill voids to keep the construction strong, extra epoxy, extra weight.

[tonyj]

Check out DaveL's Bluebonnet Tear Version 2 build here: http://www.tearsoftexas.com/bluebonnet_tear_version_20_build.htm

[Mstro]

For more information on foam sandwich construction, see this link

http://www.rqriley.com/frp-foam.htm

Hope it helps

[oklahomajewel]

Check out DaveL's Bluebonnet Tear Version 2 build here: http://www.tearsoftexas.com/bluebonnet_tear_version_20_build.htm

Yes, Dave & Cindy's Bluebonnet version 2.0 ..... I saw the 'test' peice .
It's that foam board insulation stuff, the pink stuff? and then epoxied on each side ? can't remember if it's got fiberglass on it. But Cindy said they took the test peice and STOOD on it and it didn't even bend... Pretty cool , huh?

Anyhoo.... VERY lightweight, and I saw the galley which will act as the bulkhead , it's all wood.

[ARKPAT]

I will have to try the epoxy next. I have seen Dave's panel.

Thanks Dave for more ideas to where I can use the insulation boards.



Pat